Research On Dioxin Detection And Emission Reduction In The Process Of E-waste Treatment

Due to the upgrading and updating of electronic products and the inburst of ?foreign rubbish?,China has to deal with a large amount of electronic waste every year.The nonstandard treatment of electronic waste,especially the barbarous incineration of electronic waste,has brought serious dioxin pollution to many parts of the country.Aiming at the dioxin pollution caused by the disposal of electronic waste,the main research works were completed in the following two aspects:Firstly,the test method of original dioxin in electronic waste was studied in this paper and the pretreatment method of the common dioxin samples was optimized according to the characteristics of sample matrix of electronic waste: Select three typical samples of electronic waste —— Plastic shell of television(Main components: polyvinyl chloride),plastic shell of washer(Main components: polypropylene),circuit board(Main components: resin material,40% of metal): soxhlet extraction(methylbenzene)—FMS treatment of plastic shell samples of television,the total toxicity equivalent of dioxin was 0.4619 pg.TEQ/g;soxhlet extraction(n-hexane:dichloromethane=1:1)—FMS treatment of plastic shell samples of washer,the total toxicity equivalent of dioxin was 0.3176 pg.TEQ/g;ASE(methylbenzene)— FMS treatment of breadboard sample,the total toxicity equivalent of dioxin was 0.3573 pg.TEQ/g.The total toxicity equivalents of the three samples were lower than the limit of the national standard GB5085.6-2007 of 15 ?g TEQ/kg.The recovery rate of the 15 13C-2,3,7,8-PCDD/Fs extraction internal standard of the three pre processing methods was 52%~114%,which met the requirements of the national standard(17%~181%).The experimental results showed that the results were more accurate and reliable for the selection of different pretreatment methods for different sample substrates.The test results can be used for reference in the disposal of electronic wastes: If we only consider the dioxin pollution,landfill is the safest way under the waste disposal model with landfill-dominated in China.The control parameters of dioxin in the process of electronic waste incineration were studied in this paper: First,the design of the electronic waste incineration device and the smoke collection device had been completed.The incineration device can meet the requirements of controlling different oxygen concentration and temperature to explore the effect of oxygen and temperature on dioxin during the incineration process.Then,the explorations of the oxygen content and temperature on the incineration of dioxin had been completed in the built device.The results showed that when the oxygen content was below 30%,the generation of dioxins was positively correlated with the oxygen content,indicating that oxygen is the main oxygen source of the synthetic reaction;when the oxygen content was higher than 30%,the oxygen was mainly used to increase the combustion efficiency and dioxin formed by oxidation and reduce the formation of dioxin.As the decomposition rate of dioxin increased at high temperature,the formation of dioxin decreased with the increase of temperature;when the temperature was higher than 800 ?,the amount of dioxin generated was greatly reduced.The research results also had important reference significance for incineration of electronic wastes: if incineration is used to treat electronic wastes,the incineration conditions of anoxic and high temperature should be chosen to reduce the production of dioxins.